Chalkbrood

When I started inspecting for honey bee diseases, the first and most prevalent disease I found was chalkbrood. I first observed this disease a few weeks into the spring while inspecting a few colonies. I had seen the disease on several other occasions, so it was very easy to identify by the hard “chalk-like” mummies inside the cells. As the season progressed, I learned something from the bees and what they do when the colony has chalkbrood. The nurse bees will drag white, black and other different colored infected larvae out of the hive. These “chalk-like” mummies can be found around and in front of the entrance.
Ascosphaera apis is the fungus responsible for this bee disease. Over 20 species of chalkbrood have been discovered in North America. The true origin of chalkbrood is unknown, but most likely arrived from Europe with Megachile rotundata, the Alfalfa leafcutter bee. This species was introduced to assist with pollination demands in the United States. So you may ask, “How do honey bees become infected with chalkbrood?” Worker larvae are infected when fed pollen and honey contaminated with the spores. The spores quickly germinate and the vegetative state of the fungi will out compete the larvae for food. The larva eventually starves and develops into a chalk-like mummy.

One common way to treat is to re-queen, which may or may not clear up chalkbrood. Below I have created a gallery of images showing the various stages of chalkbrood.

Written By: Rob Snyder

Rob Snyder has written 62 post in this blog.

I currently work out of the Butte County Cooperative Extension in Oroville, CA as a Crop Protection Agent. I received my B.S. in biology from Delaware Valley College, PA. There I attained a majority of my entomological knowledge from Dr. Chris Tipping and Dr. Robert Berthold. After graduation, I was an apiary inspector for 2 years at the Department of Agriculture in Pennsylvania. In my third year there, I still inspected some colonies but I mainly focused on The Pennsylvania Native Bee Survey (PANBS) where I pinned, labeled, entered data and identified native bees to genus species. Leo Donavall assisted me in learning the basics on positive Identifications of the native bees. Around the same time I began working on coordinating kit construction and distribution for the APHIS National Honey Bee Survey. I was also fortunate to conduct many of these surveys with fellow co-worker Mike Andree and Nathan Rice of USDA/ARS throughout California. All of these experiences have led me to where I am today, working to assist beekeepers in maintaining genetic diverse colonies resistant to parasites while reducing the use of chemical treatments in colonies. The BIP Diagnostic Lab at the University of MD is in an integral part of this process by generating reports in which we can track change and report to beekeepers vital information in a timely manner which may influence their treatment decisions.

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